ZNF263 is a transcriptional regulator of heparin and heparan sulfate biosynthesis

Abstract

Heparin is the most widely prescribed biopharmaceutical in production globally. Its potent anticoagulant activity and safety makes it the drug of choice for preventing deep vein thrombosis and pulmonary embolism. In 2008, adulterated material was introduced into the heparin supply chain, resulting in several hundred deaths and demonstrating the need for alternate sources of heparin. Heparin is a fractionated form of heparan sulfate derived from animal sources, predominantly from connective tissue mast cells in pig mucosa. While the enzymes involved in heparin biosynthesis are identical to those for heparan sulfate, the factors regulating these enzymes are not understood. Examination of the promoter regions of all genes involved in heparin/heparan sulfate assembly uncovered a transcription factor-binding motif for ZNF263, a C2H2 zinc finger protein. CRISPR-mediated targeting and siRNA knockdown of ZNF263 in mammalian cell lines and human primary cells led to dramatically increased expression levels of HS3ST1, a key enzyme involved in imparting anticoagulant activity to heparin, and HS3ST3A1, another glucosaminyl 3-O-sulfotransferase expressed in cells. Enhanced 3-O-sulfation increased binding to antithrombin, which enhanced Factor Xa inhibition, and binding of neuropilin-1. Analysis of transcriptomics data showed distinctively low expression of ZNF263 in mast cells compared with other (non–heparin-producing) immune cells. These findings demonstrate a novel regulatory factor in heparan sulfate modification that could further advance the possibility of bioengineering anticoagulant heparin in cultured cells.

Editorial: Proteoglycans and Glycosaminoglycan Modification in Immune Regulation and Inflammation

“…While many publications cover proteoglycan and glycosaminoglycan (GAG) research each year, to date there is still limited knowledge about the specific roles of these macromolecules in the regulation of immune responses and homeostasis. More specifically, the transcriptional control is understudied and largely unknown (1). For this reason, we initiated this Research Topic for Frontiers in Immunology, and challenged scientists to provide findings that uncover novel functions or summarize recent progress that connect these two fields of research.…”

“…Our Research Topic underscores the diverse role that proteoglycans have in inflammation and how they control different aspects of immunological processes. However, it also demonstrates that there is still much to discover about the specific mechanisms of their action, including transcriptional and translational regulation of proteoglycan and GAG biosynthesis ( 1 ).…”

Bioengineered production of glycosaminoglycans and their analogues

“…Unfortunately, the production levels of engineering CHO cells are still relatively low in comparison with the high levels in mammalian mast cells [65]. While further increases in yield and activity could be improved by changes in the fermentation condition, feeding strategies, media composition and through genetic engineering, it is doubtful that a eukaryotic expression system could ever produce the 100 metric ton quantities needed to fill the worldwide market [69,70].…”

“…With new developments of synthetic biology and genetic engineering, metabolic engineering holds considerable promise in the biomanufacturing of GAGs and analogues. Engineering eukaryotic cells is currently achievable but cannot produce sufficient amounts to meet current market demands and will be very costly [69]. The metabolic engineering of prokaryotic organisms should offer a cost-effective large-scale method for the production of GAGs.…”

Exciting New Developments and Emerging Themes in Glycosaminoglycan Research

“…In the often confusing and highly competitive area of glycosaminoglycan (GAG)-functionalized biomaterials, decellularized preparations from lung were shown to be unable to bind key matrix-associated growth factors without replenishment with specific GAGs, 2 providing useful clarity for future studies. We saw the identification of a key element in the coordinated regulation of GAG synthesis, the transcription factor ZNF263, 3 suggesting a future for directed bioengineering of designer GAGs. Moving on to the role of GAGs in regulating cell signaling, there were many exciting new stories.…”